Having spent the beginning of her career as a performer, M.J. now works regularly as a voice teacher, vocal coach, pianist, and vocalist. She has been on the Vocal Faculty at Sheridan College in the Music Theatre Performance program since 2015, and has taught at Randolph Academy for the Performing Arts, and Wilfred Laurier Conservatory’s Music Theatre Academy. Her voice and vocal coaching students have performed in Mirvish Productions, the Stratford Festival, Drayton Entertainment, and many other theatres across Canada and the US.

M.J. has worked as a Vocal Director for Disney Cruise Line and has music directed numerous stage shows for theatre companies including Thousand Islands Playhouse, and Silver Mist Productions. As a keyboardist, she has performed with the Broadway Across Canada tour of "Wicked", Drayton Entertainment's production of “Les Misérables”, and the Toronto production of "Jersey Boys".

M.J. is the owner of M.J. Johnson Voice Studio in Kitchener.